Surface treatment method for electroplating conductor roll and electroplating conductor roll

ABSTRACT

[Problem] To limit adhesion of foreign matter stemming from plating liquid, metal stemming from the plated steel sheet and oxides of the metal to the surface of a conductor roll. 
     [Solution] A surface treatment method for surface-treating the roll surface of an electroplating conductor roll characterized in that: the surface treatment liquid is a surface treatment solution in which graphite has been dispersed in a mixed solution made of an aqueous aluminum phosphate solution and colloidal silica; and that the surface treatment liquid, in which concentrations have been adjusted such that when the surface treatment liquid is 100 mass %, the aluminum phosphate content is 3 mass % to 14 mass %, the silica content is 7 mass % to 37 mass %, and the graphite content is at least 4 mass %, is supplied to the roll surface and baked.

TECHNICAL FIELD

The present invention relates to a technique for preventing foreignmaterials from adhering to a roll surface of an electroplating conductorroll.

BACKGROUND ART

In the electroplating line of cold-rolled steel sheets, the platingtreatment is performed through a series of processes including an alkalicleaning process, a pickling process, a plating process, a cleaningprocess, and a chemical treatment process while conveying thecold-rolled steel sheet.

In the plating process, a plurality of conductor rolls is installed.Here, the conductor roll is to energize the cold-rolled steel sheetconveyed in a plating bath. Metal, which is a component of the platingliquid, or its oxide easily adheres to the conductor roll as a foreignmaterial. This is because the plating liquid adhering to the conductorroll is electrodeposited by electroplating, and the plating liquid isdried and solidified on the surface of the conductor roll. As anothercause, it is conceivable that the plated metal of the steel sheet or theoxide of the plated metal adheres and is fixed to the conductor roll dueto the contact and friction between the plated steel sheet and theconductor roll.

An asperity portion is formed on the roll surface of the conductor rollin order to obtain a frictional force necessary for conveying thecold-rolled steel sheet. Therefore, the asperity portion of the rollsurface may be worn by the foreign materials that adheres at the time ofconveyance of the cold-rolled steel sheet, whereby the cold-rolled steelsheet may slip.

When the cold-rolled steel sheet slips, the cold-rolled steel sheetbends due to an impact at the time of slipping, and a gap is formedbetween the cold-rolled steel sheet and the conductor roll. When a gapis formed between the cold-rolled steel sheet and the conductor roll,the contact area of the cold-rolled steel sheet and the conductor rollis reduced. Therefore, abnormal discharge may occur, and the life of theconductor roll may be shortened.

Patent Literature 1 discloses a doctoring device for a conductor rollwhich is used to scrape off foreign materials that adheres to a rollsurface, by pressing a cutting edge, which is formed on a front edge ofa doctoring blade, against a roll surface of a rotating conductor roll.Patent Literature 2 discloses a method of removing attached metal byreverse electrolysis or the like. Patent Literature 3 discloses a methodof preventing energization to a conductor roll by a shield plate or thelike.

Patent Literature 4 discloses a method of forming a composite coatingfilm having corrosion resistance and withstanding long-term use, whichis characterized by forming a glassy surface layer film, although thetechnique belongs to a technical field different from that of aconductor roll. The glassy surface film is formed by the followingmethod: A single metal, alloy, cermet or ceramic is sprayed onto asubstrate surface having been pre-processed for thermal spraying. Afterthat, a pore-sealing liquid having a good permeability for forming apore-sealing substance in pores in the thermal spray coating film isapplied or impregnated, and then aged or heat-treated to perform asealing treatment. After that, a solution in which a glassy materialforming component is dissolved or suspended is applied by brushing orspraying. The resulting article is dried at room temperature or baked ata temperature of 900° C. or lower to form the glassy surface layer film.Further, as a pore-sealing agent, there has been disclosed thosecontaining an inorganic colloidal liquid containing SiO₂ and the like,and a phosphate-based inorganic binder.

Patent Literature 5 discloses a surface hardening treatment method,which is characterized by performing a pore-sealing treatment, althoughit belongs to a technical field different from that of a conductor roll.The pore-sealing treatment is performed by forming a porous coating filmon a sliding portion of a nuclear power equipment or the like by athermal spraying method, applying a graphite-containing liquid to theporous coating film, and baking the porous coating film.

CITATION LIST Patent Literature

Patent Literature 1: JP2013-151716

Patent Literature 2: JPH1-162798

Patent Literature 3: JPS63-50495

Patent Literature 4: JP2001-152307

Patent Literature 5: JPH2-298587

SUMMARY OF INVENTION Technical Problem

However, in the configuration of Patent Literature 1, a doctoring devicefor scraping off foreign materials is required. This configuration thuscomplicates the plating line and increases the costs. Further, thedoctoring device is exposed to a large amount of plating liquid vapor orthe like. Therefore, there is a problem that the maintenance isdifficult and the replacement frequency of parts is high as comparedwith a doctoring device used for a roll for iron making, a roll for apaper machine, or the like. In addition, the thermal spray layer may bedamaged and have to be re-sprayed when the cutting edge impinges on thesurface of the conductor roll (e.g., the thermal spray layer).

Further, in Patent Literatures 2 and 3, during removal of the attachedforeign materials, the use of the conductor roll must be temporarilyinterrupted. Therefore, the productivity of the plated steel sheets islowered.

In Patent Literature 4, it is described that a thermal spray coatingfilm is subjected to a pore-sealing treatment and the surface layerthereof is coated with a glassy film to close through pores and obtainexcellent corrosion resistance against molten metal, acid, alkali, orcorrosive gas. However, the above-mentioned problem of the conductorroll (i.e., the adhesion of foreign materials) is not considered. Inaddition, the specification in paragraph 0001 describes “a method ofmanufacturing a coating film that has a high voltage resistance and isunlikely to generate a corona discharge”. As can be seen from thisdescription, the technique of Patent Literature 4 also aims to insulatethe coating film, and does not target conductor rolls havingconductivity in the first place.

Further, Patent Literature 5 describes that wear resistance can beenhanced, and the friction coefficient can be lowered and seizing can beprevented by applying a graphite-containing liquid as a lubricant to aporous coating film, and baking it to perform a pore-sealing treatment.However, the above-mentioned problem of the conductor roll (i.e., theadhesion of foreign materials) is not considered.

Solution to Problem

In order to solve the above-described problems, the inventors of thepresent application has found that a conductor roll is subjected to asurface treatment using a mixed aqueous solution containing 3 to 14 mass% of aluminum phosphate, 7 to 37 mass % of silica, and 4 mass % or moreof graphite, so that a conductive property and an effect of preventingadhesion of foreign materials can be imparted to the outermost layer ofthe conductor roll. The present invention has thus been completed.

Advantageous Effects of Invention

According to the present invention, foreign materials derived from theplating liquid, metal derived from the plated steel sheet, and oxide ofthe metal can be prevented from adhering to the surface of the conductorroll.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of a vertical continuous electroplating cell.

FIG. 2 is a front partial cross-sectional view of a conductor roll.

FIG. 3 is a schematic view of a test instrument for evaluating an effectof preventing adhesion of foreign materials.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is a schematic view of a vertical continuous electroplating cellto which a conductor roll according to an embodiment of the presentinvention is applied. With reference to the same drawing, a plating tank11 is provided in multiple stages. A plating liquid M is stored in eachof the plating tanks 11. In FIG. 1, only one of the plating tanks 11 isillustrated, and the other plating tanks are omitted. Examples of theplating liquid M include well-known ones such as those for zinc plating,nickel plating, tin plating, and the like. In tin plating, inparticular, tin oxide (SnO) and metal tin tend to adhere to a conductorroll because tin has a low melting point and is a relatively soft metal.Therefore, the present invention is particularly suitable when appliedto tin plating. A sink roll 12 is installed in the plating tank 11. Theconveying direction of a metal strip S is changed from a downwarddirection to an upward direction by the sink roll 12. A pair ofelectrode plates 13 is disposed at a position where the metal strip S isinterposed therebetween on each of the upstream and downstream sides ofthe sink roll 12.

A conductor roll 14 is disposed between adjacent plating tanks 11. Theconveying direction of the metal strip S is changed from the upwarddirection to the downward direction by the conductor roll 14. Here, theplating liquid M adheres to the metal strip S discharged from theplating tank 11. Therefore, when the metal strip S reaches the conductorroll 14, the plating liquid M adheres to the roll surface of theconductor roll 14.

An anode of a not-illustrated DC power source is connected to theelectrode plate 13, and a cathode thereof is connected to the conductorroll 14, and a voltage is applied to these electrode plates to energizebetween the electrode plate 13 and the strip S. As a result, the surfaceof the strip S conveyed in the plating tank 11 can be continuouslysubjected to a plating treatment. However, the present invention canalso be applied to a horizontal continuous electroplating cell in whichthe conductor roll 14 is constantly immersed in the plating liquid M.

FIG. 2 is a front partial cross-sectional view of the conductor roll. Athermal spray coating film 14 b is formed on the surface of a rollbarrel portion 14 a of the conductor roll 14. As the thermal spraycoating film 14 b, for example, a thermal spray coating film containingWC, Cr₂C₃, and Ni, a thermal spray coating film containing WC, Cr₂C₃,and Cr, a thermal spray coating film containing WC, Cr₂C₃, and NiCr, athermal spray coating film containing WC, Cr₂C₃, and NiCrW, or the likecan be used.

A surface treatment layer 14 c (which corresponds to a foreign materialadhesion prevention layer) is formed on the surface of the thermal spraycoating film 14 b. The surface treatment layer 14 c is formed byapplying a predetermined surface treatment liquid to the thermal spraycoating film 14 b and baking the same. The application method may bebrushing or spray coating. The baking treatment can be performed in anelectric furnace. The baking temperature is preferably 150° C. or lower.The surface treatment liquid is obtained by dispersing graphiteparticles in a mixed solution of an aluminum phosphate aqueous solutionand colloidal silica. However, the surface treatment layer 14 c may beformed directly on a base material of the conductor roll 14. That is,the surface treatment layer 14 c of the present invention can also beapplied to the conductor roll 14 without the thermal spray coating film14 b.

(Aluminum Phosphate Aqueous Solution)

When the entire amount of the surface treatment liquid is 100 mass %,the concentration of aluminum phosphate is 3 mass % or more and 14 mass% or less, and preferably 6 mass % or more and 11 mass % or less. If thecontent of aluminum phosphate is less than 3 mass %, colloidal silicacannot be sufficiently gelled. As a result, dripping may occur on thesurface of the conductor roll and the distribution of graphite maybecome uneven. If the content of aluminum phosphate exceeds 14 mass %,colloidal silica gels before being applied to the thermal spray coatingfilm 14 b (i.e., gels at an early stage) and cannot be applied.

As aluminum phosphate, one kind or two or more kinds of aluminumdihydrogen phosphate (Al(H₂PO₄)₃), aluminum hydrogen phosphate(Al₂(HPO₄)₃), and monomethyl aluminum phosphate (Al[(O)P(O)OH(OCH₃)]₃)and an aluminum phosphate ester may be used.

However, when the amount of aluminum phosphate is 100 mass %, it ispreferable to contain at least 70 mass % or more of aluminum dihydrogenphosphate (Al(H₂PO₄)₃) or at least 70 mass % or more of monomethylaluminum phosphate (Al[(O)P(O)OH(OCH₃)]₃).

The present inventor also conducted an experiment of surface treatmentof the thermal spray coating film 14 b using a surface treatment liquidin which graphite is dispersed in a mixed solution of an aqueoussolution containing a phosphate compound (for example, sodiummetaphosphate (NaPO₃)) other than aluminum phosphate and colloidalsilica. However, a high effect of preventing adhesion of foreignmaterials could not be obtained. Although the mechanism is not clear, ahigh effect of preventing adhesion of foreign materials was not obtainedunless the surface treatment liquid prepared by dispersing graphite in amixed solution of an aluminum phosphate aqueous solution and colloidalsilica was used. This issue will be clarified in examples describedlater.

(Colloidal Silica)

The colloidal silica is obtained by dispersing fine particles of silica(SiO₂) in water, and may contain a small amount of a dispersant or thelike as required. When the entire amount of the surface treatment liquidis 100 mass %, the concentration of silica (SiO₂) is 7 mass % or moreand 37 mass % or less, and preferably 15 mass % or more and 25 mass % orless. Silica (SiO₂) functions as an aggregate for the surface treatmentlayer 14 c, and gels to fix graphite in the surface treatment layer 14c. If the content of silica (SiO₂) is less than 7 mass %, the effect offixing graphite in the surface treatment layer 14 c is reduced. If thecontent of silica (SiO₂) exceeds 37 mass %, many cracks are generated inthe surface treatment layer 14 c and the surface treatment layer 14 cwould be peeled off.

The present inventor also conducted an experiment of surface treatmentof the thermal spray coating film 14 b using a surface treatment liquidin which graphite is dispersed in a mixed solution of colloids otherthan colloidal silica and an aluminum phosphate aqueous solution.However, in the formed surface treatment coating film, many cracks weregenerated, the film quality of the coating film was poor, and theproblem of delamination occurred. In addition, since the dispersion ofgraphite did not proceed uniformly in the process of solating colloidsother than colloidal silica and aluminum phosphate, a high effect ofpreventing adhesion of foreign materials could not be obtained. Althoughthe mechanism is not clear, a high effect of preventing adhesion offoreign materials was not obtained unless a surface treatment liquidprepared by dispersing graphite in a mixed solution of an aluminumphosphate aqueous solution and colloidal silica was used. This issuewill be clarified in the examples described later.

(Graphite)

When the entire amount of the surface treatment liquid is 100 mass %,the concentration of graphite is 4 mass % or more, and preferably 6 mass% or more. Graphite prevents adhesion of foreign materials and impartsconductivity to the surface treatment layer 14 c. If the concentrationof graphite is less than 4 mass %, foreign materials may adhere to thesurface treatment layer 14 c, and the conductor roll 14 may not be usedat an early stage.

The upper limit value of the concentration of graphite is notparticularly defined, but is preferably 14 mass % or less, and morepreferably 11 mass % or less. If the concentration of graphite exceeds14 mass %, the contents of aluminum phosphate and silica (Si) arelowered, so that there is a possibility that the surface treatment layer14 c cannot be formed.

The above-mentioned surface treatment liquid is applied to the thermalspray coating film 14 b of the conductor roll 14 and baked to form thesurface treatment layer 14 c containing alumina (Al₂O₃), diphosphoruspentaoxide (P₂O₅), silicon dioxide (SiO₂), and graphite. Incidentally,the surface treatment layer 14 c may contain impurities other than theabove-mentioned components (for example, solid substances generated whena dispersant added to colloidal silica is baked). However, since theamount thereof is negligibly small, a detailed description thereof isomitted.

Here, alumina (Al₂O₃) and diphosphorus pentaoxide (P₂O₅) are compoundsderived from the aluminum phosphate solution. When the concentration ofaluminum phosphate with respect to the surface treatment liquid isadjusted to 3 mass % or more and 14 mass % or less, the content ofalumina (Al₂O₃) in the surface treatment layer 14 c becomes 1.5 mass %or more and 6.8 mass % or less, and the content of diphosphoruspentaoxide (P₂O₅) becomes 6 mass % or more and 27.3 mass % or less. Inaddition, when the concentration of aluminum phosphate with respect tothe surface treatment liquid is adjusted to 6 mass % or more and 11 mass% or less, the content of alumina (Al₂O₃) in the surface treatment layer14 c is 3 mass % or more and 5.5 mass % or less, and the content ofdiphosphorus pentaoxide (P₂O₅) is 13 mass % or more and 23 mass % orless.

Silicon dioxide (SiO₂) is a compound derived from colloidal silica. Whenthe concentration of silica with respect to the surface treatment liquidis adjusted to 7 mass % or more and 37 mass % or less, the content ofsilicon dioxide (SiO₂) in the surface treatment layer 14 c becomes 18mass % or more and 80% or less. Further, when the concentration ofsilica with respect to the surface treatment liquid is adjusted to 15mass % or more and 25 mass % or less, the content of silicon dioxide(SiO₂) in the surface treatment layer 14 c becomes 37 mass % or more and65 mass % or less.

When the concentration of graphite with respect to the surface treatmentliquid is adjusted to 4 mass % or more and 14 mass % or less, thecontent of graphite in the surface treatment layer 14 c becomes 10.2mass % or more and 36 mass % or less. When the concentration of graphitewith respect to the surface treatment liquid is adjusted to 6 mass % ormore and 11 mass % or less, the content of graphite in the surfacetreatment layer 14 c becomes 17 mass % or more and 27 mass % or less.

A more specific description regarding the present invention will now begiven by showing examples.

(Evaluation Test for Effect of Preventing Adhesion of Foreign Materials)

A predetermined sample was prepared, and the state in which foreignmaterials were attached and the amount of foreign materials attachedwere measured to evaluate the effect of preventing adhesion of foreignmaterials. FIG. 3 is a schematic view of a test instrument forevaluating the effect of preventing adhesion of foreign materials. Asshown in the drawing, a thermal spray test piece 1 and a thermal spraytest piece 1′ were stacked and a foreign material powder 2 composed of50 mass % of tin (Sn) and 50 mass % of tin oxide (SnO) was placedbetween them (i.e., between the thermal spray surface B and the thermalspray surface C) as a build-up source. In addition, the foreign materialpowder 2 was also dispersed as a build-up source onto the thermal spraysurface A, which was the upper surface of the thermal spray test piece1. Reciprocating motions of a half-moon-shaped roll 3 in the directionof an arrow X2 were performed while applying a load by pressing thehalf-moon-shaped roll 3 against the thermal spray surface A in thedirection of an arrow X1, whereby the state in which foreign materialswere attached was evaluated for each of the thermal spray surfaces A toC. In addition, the foreign material powder 2 was changed to nickel (Ni)powder, and the state in which foreign materials were attached wasevaluated by the same test method.

The thermal spray surfaces A to C were formed by a WC—Cr₂C₃—WNiCr-based(67% W-13% Cr-14.2% Ni-5.8% C by mass) cermet thermal spray coatingfilm. The composition of the surface treatment liquid applied to thethermal spray surfaces A to C was changed variously. As the aluminumphosphate aqueous solution, a mixed solution in which aluminumdihydrogen phosphate and aluminum hydrogen phosphate were mixed wasused. When the amount of aluminum phosphate was 100 mass %, the contentof aluminum hydrogen phosphate was limited to 20 mass % or less, and theremainder was aluminum dihydrogen phosphate.

In the evaluation, a score was assigned to each of the thermal spraysurfaces A to C according to the attachment state of the foreignmaterials, and the effect of preventing adhesion of foreign materialswas evaluated on the basis of the total number of points (MN number).When the foreign material powder 2 was dropped off with the thermalspray test pieces 1 and 1′ directed vertical, the effect of preventingadhesion of foreign materials was very good and three points were given.When the foreign material powder 2 was dropped off by rubbing withgauze, the effect of preventing adhesion of foreign materials wasgenerally good and two points were given. When the foreign materialpowder 2 was dropped off by rubbing with tweezers, the effect ofpreventing adhesion of foreign materials was poor and one point wasgiven. When the foreign material powder 2 was not dropped off even bythe above-mentioned methods, the effect of preventing adhesion offoreign materials was extremely poor and 0 points were given.

After the reciprocating motion of the half-moon-shaped roll 3 describedabove, the amount (mass %) of Sn adhering to the thermal spray surfacesA to C (the amount (mass %) of Ni) was measured using an X-rayfluorescence measuring apparatus. These averages were calculated. Thetest results are shown in Tables 1 to 4. When the MN value was more than7 and the Sn adhesion amount (Ni adhesion amount) was 2 mass % or less,the effect of preventing adhesion of foreign materials was evaluated asextremely good and the evaluation “AA” was assigned. When the MN valuewas 5 or more and 7 or less and the Sn adhesion amount (Ni adhesionamount) was 5 mass % or less, the effect of preventing adhesion offoreign materials was evaluated as good and the evaluation “A” wasassigned. When the MN value was 3 or more and less than 5 and the Snadhesion amount (Ni adhesion amount) was more than 5 mass % and 8 mass %or less, the effect of preventing adhesion of foreign materials wasevaluated as fault and the evaluation “B” was assigned. When the MNvalue was less than 3, regardless of the Sn adhesion amount (Ni adhesionamount), the evaluation “C” was assigned as having no effect ofpreventing adhesion of foreign materials. In Table 1, the numericalvalues expressed with “mass %” are the concentration of aluminumphosphate, the concentration of silica (SiO₂), and the concentration ofgraphite when the entire amount of the surface treatment liquid is 100mass %.

TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6Curing Agent Aluminum Phosphate Aqueous Solution 7 mass % 3 mass % 14mass % 6 mass % 11 mass % 7 mass % (Phosphate-based) SodiumMetaphosphate Aqueous Solution (Phosphate-based) Colloid LiquidColloidal Silica 22 mass %  22 mass %  22 mass % 22 mass %  22 mass % 7mass % Colloidal Alumina Colloidal Titanium Additive Graphite 9 mass % 9mass %  9 mass % 9 mass %  9 mass % 9 mass % Evaluation of MN number 8 79 8 7 5 Adhesion of Sn Adhesion Amount (mass %) 0.6 0.6 0.4 0.7 0.8 2.2Foreign Material Overall Evaluation AA A AA AA AA A Example 7 Example 8Example 9 Example 10 Example 11 Curing Agent Aluminum Phosphate AqueousSolution 7 mass % 7 mass % 7 mass % 7 mass %  7 mass % (Phosphate-based)Sodium Metaphosphate Aqueous Solution (Phosphate-based) Colloid LiquidColloidal Silica 37 mass %  15 mass %  25 mass %  22 mass %  22 mass %Colloidal Alumina Colloidal Titanium Additive Graphite 9 mass % 9 mass %9 mass % 4 mass % 14 mass % Evaluation of MN number 5 8 9 5 9 Adhesionof Sn Adhesion Amount (mass %) 3.4 0.8 0.3 4.3 0.4 Foreign MaterialOverall Evaluation A AA AA A AA

TABLE 2 Example 12 Example 13 Example 14 Example 15 Example 16 Example17 Curing Agent Aluminum Phosphate Aqueous 7 mass % 3 mass % 14 mass % 6mass % 11 mass % 7 mass % Solution (Phosphate-based) SodiumMetaphosphate Aqueous Solution (Phosphate-based) Colloid LiquidColloidal Silica 22 mass %  22 mass %  22 mass % 22 mass %  22 mass % 7mass % Colloidal Alumina Colloidal Titanium Additive Graphite 9 mass % 9mass %  9 mass % 9 mass %  9 mass % 9 mass % Evaluation of MN number 7 77 7 6 7 Adhesion of Ni Adhesion Amount (mass %) 2 2.1 2.3 1.6 2.5 2.2Foreign Material Overall Evaluation A A A A A A Example 18 Example 19Example 20 Example 21 Example 22 Curing Agent Aluminum Phosphate AqueousSolution 7 mass % 7 mass % 7 mass % 7 mass %  7 mass % (Phosphate-based)Sodium Metaphosphate Aqueous Solution (Phosphate-based) Colloid LiquidColloidal Silica 37 mass %  15 mass %  25 mass %  22 mass %  22 mass %Colloidal Alumina Colloidal Titanium Additive Graphite 9 mass % 9 mass %9 mass % 4 mass % 14 mass % Evaluation of MN number 5 7 8 5 7 Adhesionof Ni Adhesion Amount (mass %) 3.3 1.9 1.7 3.2 2.1 Foreign MaterialOverall Evaluation A A AA A A

It was found that Examples 1 to 11 and Examples 12 to 22 were excellentin the effect of preventing adhesion of foreign materials to tin (Sn)and nickel (Ni). In addition, it was found that the effect of preventingadhesion of foreign materials to tin (Sn) was particularly high. InExample 2, since the concentration of aluminum phosphate was slightlylow, the dispersion of graphite was slightly insufficient, and theoverall evaluation was not AA but A. In Example 6, since theconcentration of silica contained in colloidal silica with respect tothe surface treatment liquid was slightly low, the effect of fixinggraphite was slightly lowered, and the evaluation on the effect ofpreventing adhesion of foreign materials was not AA but A. In Example 7,since the concentration of silica contained in colloidal silica withrespect to the surface treatment liquid was slightly high, slightcracking was generated in a part of the thermal spray coating film, andthe evaluation on the effect of preventing adhesion of foreign materialswas not AA but A. In Example 10, since the content of graphite wasslightly low, the evaluation on the effect of preventing adhesion offoreign materials was not AA but A.

TABLE 3 Comparative Comparative Comparative Comparative ComparativeExample 1 Example 2 Example 3 Example 4 Example 5 Curing Agent AluminumPhosphate Aqueous Solution 7 mass % 7 mass % 7 mass % 10 mass %(Phosphate-based) Sodium Metaphosphate Aqueous 7 mass % Solution(Phosphate-based) Colloid Liquid Colloidal Silica 22 mass %  27 mass %Colloidal Alumina 22 mass %  12 mass % Colloidal Titanium 22 mass %  10mass % Additive Graphite 9 mass % 9 mass % 9 mass %  9 mass % Evaluationof MN number 3 0 1 2 0 Adhesion of Sn Adhesion Amount (mass %) 5.4 12.517.9 16 18.8 Foreign Material Overall Evaluation B C C C C ComparativeComparative Comparative Comparative Comparative Example 6 Example 7Example 8 Example 9 Example 10 Curing Agent Aluminum Phosphate AqueousSolution 2 mass % 15 mass % 7 mass % 7 mass % 7 mass % (Phosphate-based)Sodium Metaphosphate Aqueous Solution (Phosphate-based) Colloid LiquidColloidal Silica 22 mass %  22 mass % 5 mass % 40 mass %  22 mass % Colloidal Alumina Colloidal Titanium Additive Graphite 9 mass %  9 mass% 9 mass % 9 mass % 3 mass % Evaluation of MN number — — 3 3 4 Adhesionof Sn Adhesion Amount (mass %) — — 5.7 5.4 7.8 Foreign Material OverallEvaluation Unevaluable Unevaluable B B B

TABLE 4 Comparative Comparative Comparative Comparative ComparativeExample 11 Example 12 Example 13 Example 14 Example 15 Curing AgentAluminum Phosphate Aqueous Solution 7 mass % 7 mass %  7 mass % 10 mass% (Phosphate-based) Sodium Metaphosphate Aqueous 7 mass % Solution(Phosphate-based) Colloid Liquid Colloidal Silica 22 mass %  27 mass %Colloidal Alumina 22 mass %  12 mass % Colloidal Titanium 22 mass %  10mass % Additive Graphite 9 mass % 9 mass % 9 mass %  9 mass % Evaluationof MN number 2 2 1 2 1 Adhesion of Ni Adhesion Amount (mass %) 9.3 16.713.9 11.1 16.2 Foreign Material Overall Evaluation C C C C C ComparativeComparative Comparative Comparative Comparative Example 16 Example 17Example 18 Example 19 Example 20 Curing Agent Aluminum Phosphate AqueousSolution 2 mass % 15 mass % 7 mass % 7 mass % 7 mass % (Phosphate-based)Sodium Metaphosphate Aqueous Solution (Phosphate-based) Colloid LiquidColloidal Silica 22 mass %  22 mass % 5 mass % 40 mass %  22 mass % Colloidal Alumina Colloidal Titanium Additive Graphite 9 mass %  9 mass% 9 mass % 9 mass % 3 mass % Evaluation of MN number — — 2 3 2 Adhesionof Ni Adhesion Amount (mass %) — — 9.2 6.6 8.9 Foreign Material OverallEvaluation Unevaluable Unevaluable C B C

With reference to Comparative Example 1 and Example 1 for comparison, bychanging the aluminum phosphate aqueous solution to a sodiummetaphosphate aqueous solution, the evaluation on the effect ofpreventing adhesion of foreign materials became B. With reference toComparative Example 11 and Example 12 for comparison, by changing thealuminum phosphate aqueous solution to the sodium metaphosphate aqueoussolution, the evaluation on the effect of preventing adhesion of foreignmaterials became C. With reference to Comparative Example 2 and Example1 for comparison, by changing the colloidal silica to colloidal alumina,the evaluation on the effect of preventing adhesion of foreign materialsbecame C. With reference to Comparative Example 12 and Example 12 forcomparison, by changing the colloidal silica to colloidal alumina, theevaluation on the effect of preventing adhesion of foreign materialsbecame C. With reference to Comparative Example 3 and Example 1 forcomparison, by changing the colloidal silica to colloidal titanium, theevaluation on the effect of preventing adhesion of foreign materialsbecame C. With reference to Comparative Example 13 and Example 12, bychanging the colloidal silica to colloidal titanium, the evaluation onthe effect of preventing adhesion of foreign materials became C.

With reference to Comparative Example 4 and Example 1 for comparison, bychanging the colloidal silica to a mixture of colloidal alumina andcolloidal titanium, the evaluation on the effect of preventing adhesionof foreign materials became C. With reference to Comparative Example 14and Example 12 for comparison, by changing the colloidal silica to amixture of colloidal alumina and colloidal titanium, the evaluation onthe effect of preventing adhesion of foreign materials became C. InComparative Example 5 and Comparative Example 15, since graphite was notcontained, the evaluation on the effect of preventing adhesion offoreign materials became C.

In Comparative Examples 6 and 16, since the concentration of aluminumphosphate contained in the aluminum phosphate aqueous solution withrespect to the surface treatment liquid was too low, the colloidalsilica could not be gelled. Therefore, the effect of preventing adhesionof foreign materials could not be evaluated. In Comparative Examples 7and 17, since the concentration of aluminum phosphate contained in thealuminum phosphate aqueous solution with respect to the surfacetreatment liquid was too high, the surface treatment liquid gelledbefore being applied to the thermal spray coating film. Therefore, sincethe surface treatment liquid could not be applied to the thermal spraycoating film, the effect of preventing adhesion of foreign materialscould not be evaluated.

In Comparative Example 8, since the concentration of silica contained incolloidal silica with respect to the surface treatment liquid was toolow, the effect of fixing graphite was greatly lowered, and theevaluation on the effect of preventing adhesion of foreign materialsbecame B. In Comparative Example 18, since the concentration of silicacontained in colloidal silica with respect to the surface treatmentliquid was too low, the effect of fixing graphite was greatly lowered,and the evaluation on the effect of preventing adhesion of foreignmaterials became C.

In Comparative Examples 9 and 19, since the concentration of silicacontained in colloidal silica with respect to the surface treatmentliquid was too high, the effect of fixing graphite was greatly lowered,and the evaluation on the effect of preventing adhesion of foreignmaterials became B. In Comparative Example 10, since the content ofgraphite contained in the surface treatment liquid was too small, theevaluation on the effect of preventing adhesion of foreign materialsbecame B. In Comparative Example 20, since the content of graphitecontained in the surface treatment liquid was too small, the evaluationon the effect of preventing adhesion of foreign materials became C.

REFERENCE SIGNS LIST

-   -   11 plating tank    -   12 sink roll    -   13 electrode plate    -   14 conductor roll    -   15 roll polisher

1. A surface treatment method for an electroplating conductor roll,performing a surface treatment of a roll surface of an electroplatingconductor roll, the method comprising: supplying a surface treatmentliquid obtained by dispersing graphite in a mixed solution comprising analuminum phosphate aqueous solution and colloidal silica to the rollsurface, the surface treatment liquid being adjusted in terms ofconcentration such that a content of aluminum phosphate is 3 mass % ormore and 14 mass % or less, a content of silica is 7 mass % or more and37 mass % or less, and a content of graphite is at least 4 mass % ormore when an amount of the surface treatment liquid is 100 mass %; andbaking the roll surface.
 2. The surface treatment method for anelectroplating conductor roll according to claim 1, wherein theelectroplating conductor roll includes a roll main body and a thermalspray coating film obtained by thermally spraying a surface of the rollmain body, and the surface treatment liquid is supplied to the thermalspray coating film.
 3. The surface treatment method for anelectroplating conductor roll according to claim 1, wherein, when theamount of the surface treatment liquid is 100 mass %, the content ofgraphite is 14 mass % or less.
 4. The surface treatment method for anelectroplating conductor roll according to claim 1, wherein the aluminumphosphate aqueous solution comprises one kind or two or more kinds ofaluminum dihydrogen phosphate, aluminum hydrogen phosphate, monomethylaluminum phosphate, and an aluminum phosphate ester.
 5. Anelectroplating conductor roll comprising a foreign material adhesionprevention layer on a surface of the roll, wherein the foreign materialadhesion prevention layer contains alumina, diphosphorus pentaoxide,silicon dioxide, and graphite, a content of alumina is 1.5 mass % ormore and 6.8 mass % or less, a content of diphosphorus pentaoxide is 6mass % or more and 27.3 mass % or less, a content of silicon dioxide is18 mass % or more and 80 mass % or less, and a content of graphite is10.2 mass % or more and 36 mass % or less when an amount of the foreignmaterial adhesion prevention layer is 100 mass %.
 6. The electroplatingconductor roll according to claim 5, comprising a roll main body and athermal spray coating film obtained by thermally spraying a surface ofthe roll main body, wherein the foreign material adhesion preventionlayer seals pores of the thermal spray coating film and covers a surfaceof the thermal splay coating film.